Di- and triphenyllead sulfides having substituent radicals joined to the sulfur atom



3,322,779 Dll- AND TRIPHENYLLEAD SULFIDES HAVING SUBSTITUENT RADICALS .IOINED TO THE SULFUR ATOM Malcolm C. Henry, Harvard, Mass., and Adolf W. Krebs,

New York, N.Y., assignors, by direct and mesne assignments, to International Lead Zinc Research rganization, The, New York, N.Y., a membership corporation of New York No Drawing. Filed Apr. 1, 1963, Ser. No. 269,771 1 Claim. (Cl. 260-299) Our present invention relates to new organolead compounds containing sulfur, and more particularly to substituted tetra-valent lead compounds in which the substituent groups attached to the lead atom are phenyl radicals (either 2 or 3) and in which the groups attached to the sulfur atom, and through the sulfur atom to the lead atom, are aliphatic, or aromatic.

Further our invention relates to novel methods of making these compounds. The new compounds have been found to have valuable properties, as will be pointed out below.

In general, our new compounds are phenyllead sulfides represented by the formula where Ph is a phenyl group, and R is a radical selected from the aliphatic or aromatic groups, and n is either 2 or 3.

In general, the reaction which we have discovered for producing these compounds may be represented as follows:

The compounds Pb(SR) may first be formed by the known reaction Thus two molar equivalents of the respective mercaptan or thioacid dissolved in alcohol were dropped slowly into a refluxing 50% alcoholic solution containing one molar equivalent of lead (II) acetate. An almost immediate precipitation of the yellow lead (II) mercaptide or lead (II) salt of the thioacid takes place.

EXAMPLE 1 (a) The preparation of thiomethyl triphenyllead Stoichiometric amounts of triphenyllead chloride and lead (II) methyl mercaptide were refluxed in benzene for three hours. During this time the lead (II) methyl mercaptide was converted into white lead (II) chloride.

The lead chloride was filtered off, the benzene evaporated, and the remaining residue of. (C H PbSCH melting point l06-108 (yield: quantitative) recrystallized from hexane; M.P. of pure compound 108-l09. Mixed melting points with admixture of a known sample gave no depression.

By starting with the corresponding lead (II) ethyl mercaptide, the compound thioethyl triphenyllead may be prepared following the procedure of Example 1(a).

(b) The preparation of [hi0 n-pr0pyl triphenyllead n-Propyl lead (II) mercaptide was first prepared as given above, i.e., from stoichiometric amounts of the corresponding thiol and lead acetate in 50% aqueous alcohol,

and after washing the so-formed salt with water, it was dried in a vacuum desiccator.

Triphenyllead chloride, 4.86 g. (10 mmoles), and lead (II) n-propyl mercaptide, 1.79 g. '(5 mmoles), in 100 ml. benzene were refluxed with stirring for three hours. During this time the yellow merca-ptide was converted into white insoluble lead chloride which was filtered off at the end of the reaction period. The filtrate was evaporated and the residue recrystallized from ethanol, yield 4.84 g. M.P. 5758.

The above described new compounds are white, or slightly colored crystalline compounds, with the exception of the liquid butyl and decyl compounds. The former, the solid compounds, decompose above the melting point to a dark brown material. The liquid compounds decompose at their boiling point. All are readily soluble in benzene, n-hexane, alcohol, chloroform, and most of the other common organic solvents. The infrared absorption spectra of all compounds show, besides the usual absorptions associated with aromatic compounds and the respective group attached to the sulfur, the band at 1052 cmf typical for organolead compounds.

Methyl iodide reacted quantitatively at room temperature with thiomethyl triphenyllead to yield triphenyllead iodide and dimethyl sulfide, probably through an unstable sulfonium salt intermediate:

(OaH5)3PbI (CHahS 1 This reaction did not take place with triphenyllead thioacetate; apparently the acetyl group decreases the electron density at the sulfur atom so that formation of a sulfonium intermediate becomes impossible.

on. ouarairbsorta oHa uofinmrbp cnau Mineral acids cleaved the lead-sulfur bond preferenti-ally; however, cleavage of lead-phenyl bonds was always detected. For example, mixtures of triphenyllead chloride, diphenyllead dichloride and lead chloride were obtained from the reaction of thioalkyl triphenyllead compounds and hydrochloric acid.

This compound was prepared in exactly the same manner as set forth in Example 2(a) above, using triphenyllead chloride instead of the diphenyl compound. Its melting point is set forth in Table I, item 7, and its rodent repellent property is listed in Table III, item 4.

The other aliphatic compounds, numbers 4 and 14, Table I, were prepared following Example 1; the thiomethylcarbomethoxy compound, number 10, Table I, was prepared similarly to Example 2. Since the other compounds listed in Table I were prepared using stoichiometric quantities of the reactants, it is not necessary to restate the method in respect of each.

TABLE I Formula Compound Melting,

Point C.

1 (C H PbSCH Thiomethyl tripheuyllead 108-109 2. (C H5) PbSCzH5 Thioethyl tripheuyllead. 67-68 (CtHrdgPbsCaHv Thiopropyl tripheuyllead 57-58 (CaH5)3PbSC4H9 Thiobutyl triphenyllead (CfiH5)5PbSGHZO6H5 Thiobenzyl triphenyllead 82-83 (CtH5) PbSC H5 Thiophenyl tripheuyllead 106-107 if 7- (C HQ PbSO CH Thioacetyl tripheuyllead 92-93 I] 8. 119 10380 C H Thlobenzoyl triphenyllead 93-94 9 (C 11 PbS Thionaphthyl tripheuyllcad 73-75 ll 10 (C HQaPbSOHzC OCH; Thi0methylcarbomethoxy tripheuyllead 85 11 (C 11 PbS 0 Thiobenzthiazolyl triphenyllcad 58 12 (CGH5)2P1) SO Dithiobenzthiazolyl diphcuyllead 152-153 13. (0 11 3 19138 C Thiobenzoxazoyl triphenyllead G5 (CeH5)3PbS(CHz)9CH3 Thiodecyl triphenyllead (1) (CuH5)zPb(SCOCH )z Bisthioacetyl dipheuyllead 94-95 l Decomposed at b.p.

The foregoing compounds are presently undergoing tests in various fields. A number, including particularly thioacetyl triphenyllead, have shown activity against cell cultures at very low concentrations. Others, as for example those numbered 1 to 7 in Table I, have shown antiandrogenic activity in animal tests.

Various of our new compounds have proved to be highly useful as additives for lubricating oils, particularly for the purpose of improving their action in preventing friction and wear under boundary lubrication conditions.

Wear experiments were therefore run in the Shell Four Ball Wear Tester, which is widely used for measuring the wear prevention qualities of lubricants under boundary conditions. The device rotates a one-half inch metal ball under a specified load against three similar balls clamped together in an equilateral triangle. These balls are contained in a heated cup filled with the lubricant. The bulk temeperature of the lubricant is measured by a thermocouple inserted in a thermowell in the cup. Torque on the lower ball holder is a measure of the frictional resistance at the rubbing surfaces, and is continuously measured by means of a strain gauge and recorder. Further details of the Shell Tester may be had from Lub. Eng. 1, (1945). The rubbing of the upper ball in the presence of the lubricant against the lower three produces circular concave scars on the lower balls. With no wear, the balls will have a minimum diameter (Hertz diameter) which is the result of elastic deformation of the balls, and is determined by the modulus of elasticity of the material and the load applied. After a wear run, the three scars are measured to 0.01 mm. under a microscope, and the average diameter is a measure of the wear, and the basis for computation of the unit pressure.

The pressure in the contact zone of balls in the 4-ball test decreases greatly during the course of the test, since the load remains constant, while the area (wear scar area) supporting it, increases. With a 15 kg. load on SAE 52 steel balls, the Hertz diameter is approximately 0.22 mm., which corresponds to a pressure of 230,000 lbs./in. When the scar diameter reaches 0.5 mm., the pressure has dropped to 45,000 lbs./in.

By maintaining the bulk lubricant temperature, rotational speed, and time, constant, the performance of lubricants on the basis of time required for the contact zone pressure to decrease to a given value at a specified temperature may be evaluated.

In the tests conducted to measure the lubricating value of the lubricating oil to which the new compounds were added, the time required for the pressure to decrease to 50,000 lbs./in. was chosen as a convenient value to use in comparing relative performance.

Table II below is illustrative of results obtained by the use of our improved compounds. In carrying out the tests, white mineral oil was used as the base, and the 5 quantity of additives use-d was 1% by weight based upon the lead content. To provide a basis of comparison, the same test was run upon the compound mixed zinc dial- The results of the screening tests with certain of our new compounds are listed below:

TABLE III kyl phosphoro dithioate manufactured by Lubrisol Corporation under the trade name Lubrisol 1060, and the 5 Repenency to results given in Table II. The concentration of Lubrisol Formula o pou house No- 1060 was 4.04 weight percent. f

1 (C0H5)3PbSCOC0H Tl1i0benz0y1tri- /10 10 Pl Pb(SOH 0 II) o ii ii 'l a 10 10 2 11 2 05 20"- ie no enzy i- TABLE II phenyllead.

3 PhgPbSCsHy Thiopropyl tri- 10/10 Change in Time 4 PhgPbSCOCIIa 'r iig gii i t'ii hen- 8/10 0 t t -)tga h lead oncen ra'ion 50,000 in. Compound (Wt. percent PMSCHW iggfi 2/10 013d) M M ransom; Lead propylmer- 2 10 F o O eaptide. C' 125 O 7 Lead phenylmer- 1/10 captide. gilbaselwitgout additive 13 PMSCZHS) fi g ethylmer' 0/10 ubriso 106 50 2 $giolegthylltriphlenyageadffl 3, 001 g PMSOtHm iigfi z 0/10 10 uty trip any ea 1 1 2. 00 Thiobenzyltriphenyllead--. 2.70 *900+ PhPb Tetraphenyneaim 0/10 Thiornethyltriphenyllead 2. 34 3, 000+ 3, 000+ Thmphenylmphenynead 3000+ 19 Known compounds, 5 to 10 inclusive, are given for sake of comparison. *Not tested beyond 900 minutes.

Antzfungal actzvzly of organolead compounds A series of antifungal tests was carried out on various of our novel organolead-sulfur compounds, as indicated Varlous of our new compounds We're found to be below. The test organisms were: Bozrytis allii=B; Penifectlve as rodent repellents, and deterrents. In carrying illi i =1 Aspergillus i =A; d Rhizgpus out these tests, 25 white wheat seeds are treated wlt'h a nigricans=R. 1% concentration of the test compound, and offered to Th activity of the compound is that represented by each of 10 1101156 1111-66 for an Overnlght p of from the minimal concentration in parts per million causing 16 to 18 hours. If 13 or more seeds are uneaten, the complete inhibition of visible growth. Known compounds animal is considered to be repelled. Those compounds are given for the sake of comparison.

TABLE IV.ANTIFUNGAL ACTIVITY OF ORGANOLEAD COMPOUNDS which repel fewer than 80% of the mice, are not tested further. This test is patterned after those devised for testing the well-known repellent tetramethyl thiuran disulfid (TMTD).

We claim:

Organolead compounds selected from the group consisting of thiohenzthi-azolyl triphenyllead, dithiobenzthiazolyl diphenyllead and thiobenZox-azoyl triphenyllead.

References Cited UNITED STATES PATENTS 2,044,934 6/1936 Calcott et a1. 167 22 2,789,104 4/1957 Ramsden 61; al. 260-45.75 3,073, 853 1/1963 Ballinger 260-437 3,073,854 1/1963 Ballinger 260-437 3,031,325 3/1963 Ballinger 260-437 3,142,614 7/1964 Ligett 167-22 OTHER REFERENCES Leeper et 211., Chemical Reviews, vol. 54, No. l, (1964), pp. 136 to 152.

TOBIAS E. LEVOW, Primary Examiner. HELEN M. MCCARTHY, Examiner. E. C. BARTLETT, H. M. S. SNEED,

Assistant Examiners. 

